s well when you are happy. But what

s well when you are happy. But what exactly is happiness? I’m not asking what happiness is affected by, but what it actually is. The different ways in which we define happiness affect what we can do to improve it. So a clear definition should be, but rarely is, a fundamental concern for any book on happiness. Having worked at the interface of economics, psychology, philosophy, and policy for two decades, I think I am well placed to make a strong case for the following definition: happiness is experiences of pleasure and purpose over time. This definition is novel, it’s coherent, and it resonates with people in my research and in my life; and I hope it will with you, too. It is also measurable, which is vital if we are to advance our understanding of happiness. Now let’s take a step back.

Happiness as evaluation

Happiness has not typically been measured in this experience-based way; rather, it has been assessed using evaluations of how well life is going overall. A personal anecdote illustrates the difference nicely. A few weeks ago, I went out for dinner with one of my best friends, whom I have known for a long time. She works for a prestigious media company and basically spent the whole evening describing how miserable she was at work; she variously moaned about her boss, her colleagues, and her commute. At the end of dinner, and without a hint of irony, she said, “Of course, I love working at MediaLand.”

There is actually no real contradiction here: she is experiencing her work in one way and evaluating it in another way. The distinction between experience and evaluation is rather like the difference between being filmed and having your photograph taken. My friend was describing the daily “film” of her job as miserable and the overall “snapshot” as quite satisfying in comparison.

We shall see that this is not only a common thing to do but it’s also a common mistake to make about our happiness. Many of the assumptions we make about happiness and about ourselves have a lot to do with the fact that we generally pay more attention to what we think should make us happy rather than focusing on what actually does. My friend is not happy at work but her experiences have less influence on her behavior than do her evaluations. She loves the idea of working at MediaLand and this is what she acts upon. As a result, she is less happy, day to day, than she could be.

Satisfaction with particular aspects of life, such as work, health, and relationships, will often predict what we do – just as my friend’s relatively positive evaluation of working at MediaLand means that she could stay put - but measures of satisfaction are still not very well placed to capture how we feel. My friend is pretty miserable at work, and we should be taking that into account when we measure her happiness.

Most happiness surveys ask rather vague and abstract questions like “Overall, how satisfied are you with your life?” as well as about satisfaction with particular aspects of life. Of course, one question can never really get at all the complex aspects of happiness, but single questions can help us to approximate what makes most people happy or unhappy. The real problem with this question, however, is that overall life satisfaction is rarely considered in our daily lives; perhaps it is only ever really triggered in studies that measure it. The word “satisfaction” is also problematic since it is open to many different interpretations, including “having just about enough,” which does not really measure happiness at all. As such, the results tell us much more about what pops into your head when you answer these questions than they do about your experiences of happiness on a day-to-day basis. And it literally must be what “pops” in, because the time taken to answer what to me feels like a cognitively demanding question is around five seconds.

This helps to explain why responses to life satisfaction questions seem to be affected by apparently irrelevant factors, such as whether or not you are asked about your political views before being asked a life satisfaction question, where the effect is nearly as large as becoming un-employed. The order of the questions you’re asked matters a lot, too. Your satisfaction with life is much more highly correlated with your marital satisfaction if the marriage question comes before the life satisfaction question instead of after it: being reminded about your relationship first makes it more important in determining your life satisfaction.

You “pose” in a particular way when you have your photograph taken. Think of all the times you have posed for the camera in ways that do not reflect your current feelings. A camcorder is much better at showing how happy you are over time. So we need to move away from global snapshots of overall life satisfaction and instead focus more directly on our day-to-day feelings.